"the bitterest dregs of slavery" is a metaphor. Douglass compares his experience with Mr. Covey to the bitter, leftover stuff at the bottom of the cup. He uses this metaphor to demonstrate how unbearable life was in this time period.
IDENTIFY THE RHETORICAL DEVICE
SHOWED HOW IT IS AN EXAMPLE OF THAT DEVICE
EXPLAINED THE EFFECT ON THE READER
IDENTIFY THE RHETORICAL DEVICE
SHOWED HOW IT IS AN EXAMPLE OF THAT DEVICE
EXPLAINED THE EFFECT ON THE READER